To study in an animal sepsis model: a) the immunologic status of the host by evaluating lymphocyte subpopulation dynamics and b) metabolic alterations and possible interactions with immunologic processes. To study surgical patients, trauma patients and patients with sepsis to: a) select alterations in immunologic constitution and function and correlate to the incidence and extent of infectious complication. b) define metabolic alterations and determine the nature of myocardial failure in sepsis.